Shooting in and Dark arena

[gsgary]

You can forget it with that lens

Oh thanks. Your truley helpful...
Any tips on getting them as good as possible though?

None because it is not possible with your camera and lens, i should know i shoot indoors most winter
This shot may look like there is plenty of light but i shot at ISO3200 F3.2 1/640 @ 300mm

 

[gsgary]

Ok try ISO 1600, do not zoom your lens from 70mm (tape it up so you remember) open your aperture as wide as it will go (smallest F number probably 4.5 ? ) continuos focus, fastest frames per second, now keep your elbows tight to your side so the camea is firm, and follow the horse as it goes past, take a few shots (keep your camera on the same plain do not move up or down) if you can get in the areana even better, see what shutter speed you are getting 1/100 will give you a bit of blur in the legs you can get a higher shutter speed by going to iso 3200 it will be noisy but you can convert to B+W to give it an old film look
My partners horse shot at 1/40
http://gsgary.smugmug.com/Animals/My-Partners-Horse-Ruby/Image00008/237098402_SPSmy-XL.jpg

1/100
http://gsgary.smugmug.com/Animals/My-Partners-Horse-Ruby/Ruby4-081-after/378094502_VJWEX-XL.jpg

So dressage at 1/100 panned should get you a few shots if you get your panning correct

 

[Eventer]

Correct guess 4.5 is as low as it goes
Thank you for the advice that really was helpful
Okay well I think ill just have to play around wih the ISO and see what happens.
Thats such a awesome photo of the dog though!
I would mind a bit of the bluring like in your second example but I would prefer nice crisp shots. I think if the photo dont come out good at all Ill going out side and see how i get on
thank you!